1. Field of the Invention
The present invention generally relates to information recording techniques and, more particularly, to an information recording apparatus and method which records information on a recordable information recording medium such as a dual-layer DVD (Digital Versatile Disc+Recordable) or the like.
2. Description of the Related Art
As recordable DVD discs, there are DVD+R which is a write-once-read-many DVD disc, DVD+RW which is a rewritable DVD disc, etc. These discs are recorded DVD discs with high reproduction compatibility with reproduction-only DVD discs. Development of a technique to increase a recording speed and recording capacity has been progressed with respect to the recordable discs.
One of the discs using such a technique is a single-sided dual-layer DVD+R disc (hereinafter, referred to as “dual-layer DVD+R”) which is compatible with a single-sided dual-layer reproduction-only DVD disc. The recording capacity of the dual-layer DVD+R is 8.4 giga bytes, which is almost double the data capacity, 4.7 giga bytes, of a conventional single-layer DVD+R. Data recorded on dual-layer DVD+R can be read by a DVD-ROM drive or a DVD player that is capable of reproducing a single-sided dual-layer reproduction-only DVD disc.
Here, there are two kinds of method for the single-sided dual-layer reproduction-only DVD. One is a parallel track path method (PTP method) according to which a track of a second layer extends from an inner side to an outer side as is the same as a track of a first layer. The other is an opposite track path method (OPT method) according to which a track of a second layer extends from an outer side to an inner side. According to the PTP method, radial positions of addresses, from which data areas of the first and second layers start, are equal to each other, and each of the addresses of the data areas start from 30000H. Additionally, a lead-out area is arranged after the data area. On the other hand, according to the OTP method, the radial potion of the address at which the data area of the second layer begins is equal to the radial position of address at which the data area of the first layer ends. The physical address of the data area start position of the second layer is an address obtained by bit-inverting the data area end address of the first layer. If there is a difference in data area size between the first layer and the second layer, the difference area corresponds to the lead-out area. For example, if, in the PTP disc, an end address D1 of the data area of the first layer and an end address D2 of the data area of the second satisfy a relationship D1>D2, a difference area D1−D2 corresponds to the lead-out area. Thus, data is recorded on an area of the second layer corresponding to an area of one recording layer (first layer) where data is recorded. This is to avoid a problem, which may arise when a user reproduces data on the first layer and if a reading laser is incidentally focused on the second layer during a seeking operation to a target address, in that address information cannot be acquired if data is not recorded at the same radial position of the second layer, which may result in that data of the first layer cannot be reproduced.
Additionally, the logic address in the dual-layer DVD is continuously assigned from a start address of the data area of the first layer. Further, the logic address is continues from the data area end address of the first layer to the data area start address of the second layer. That is, when performing reproduction of data on the dual-layer DVD, the reproduction can be performed without being conscious of the recording layer.
On the other hand, when performing data recording using the dual-layer DVD+R, a user designates a recording area using a logic address similar to the reproduction operation. For this reason, if the user attempts to perform the data recording continuously, the recording is started at the data area start address of the first layer, and the recording is continued from the data area start address of the second layer after completion of the recording to the data area end address of the first layer.
Thus, it is possible to record without a user being conscious of a recording layer also in recording the dual-layer DVD+R. For this reason, there may be a case where the data recording ends in the middle of the data area of the second layer or ends without recording on the second layer. For example, if the data recording is completed in the middle of the data area of the second layer, that is, if the data recording is completed in a state where an unrecorded area is present, and if the unrecorded area remains in the data area of the second layer, the disc layout is not compatible with a reproduction-only dual-layer DVD disc. Additionally, for example, there may be a problem, which may arise when reproducing data on the first layer and if a reading laser is incidentally focused on the second layer during a seeking operation to a target address, in that address information cannot be acquired if data is not recorded at the same radial position of the second layer, which may result in that data of the first layer cannot be reproduced. Such a problem may also arise in a case where data recording is ended without recording on the second layer.